1. Field of the Invention
The invention relates to a method for finishing lenses, particularly very small lenses such as gradient index lenses.
2. Background Art
A gradient index (GRIN) lens has a refractive index that changes continuously. GRIN lenses have many uses in optical devices such as switches, isolators, couplers, wavelength division multiplexers, and circulators. GRIN lenses are made from glass rods with gradient refractive indexes. Methods for making such glass rods are well known in the art. Typically, the gradient refractive index is achieved by introducing dopants into different layers of the glass material.
The process for fabricating a GRIN lens involves cutting a desired length of a glass rod having a gradient refractive index and finishing the glass rod into a lens that has the desired dimensional and optical characteristics. The finishing process generally involves several steps. A typical sequence of steps for finishing a lens is as follows: grind the faces of the lens, lap the faces of the lens, polish the faces of the lens, clean the lens, coat the lens with an anti-reflective material, clean the lens, inspect the lens, and package the lens.
GRIN lenses are very small lenses. For example, a GRIN lens may be 1.8 mm in diameter by 4.82 mm in length, or smaller. Currently, GRIN lenses are processed one at a time through many or all of the finishing process steps described above, which is a very expensive way of finishing such small lenses. Moreover, handling glass through many or all of the finishing process steps can result in damage to the lens.
In one aspect, the invention relates to a method for producing lenses which comprises assembling a plurality of glass rods having a desired length into a single unit, cutting the single unit into multiple slices, each slice having a plurality of individual lenses, finishing the slices to a desired thickness and surface finish, and extracting the individual lenses from the slices.
In another aspect, the invention relates to a method for producing gradient index lenses which comprises assembling a plurality of glass rods having a gradient refractive index into a single unit, cutting the single unit into multiple slices, each slice having a plurality of individual lenses, finishing the slices, and extracting the individual lenses from the slices.
In another aspect, the invention relates to a method for producing lenses which comprises assembling a plurality of glass rods having a desired length into a single unit, cutting the single unit into multiple slices, each slice having a plurality of individual lenses, finishing the slices to a desired thickness and surface finish, coating the slices with an anti-reflective material, cleaning the slices, and extracting the individual lenses from the slices.
Other features and advantages of the invention will be apparent from the following description and the appended claims.